The present invention relates to solutions for winding coils of core components of dynamoelectric machines, and more particularly to apparatuses for winding stator cores, like those employed in brushless motors.
Although the invention is particularly described with reference to stator cores, the principles of the invention are equally applied to other cores that need to be wound with wire conductor.
With brushless motors it is known to use cores having wire coils wound by moving one or more needles to dispense tensioned wire. To form a coil having a plurality of turns the wire exits the moving needles and becomes appropriately positioned in the core. The needles move for a predetermined number of cycles to generate a certain number of complete turns, which form the finished wound coils.
The cycle accomplished by a needle is normally a combination of reciprocating translations, reciprocating rotations and incremental radial movements, as described for example in publication EP 1191672.
Schematically, a turn of a coil is a closed rectangular extension of wire having two rectilinear sides joined by two shorter sides. In general, a series of turns forming a coil consist of a plurality of the rectangular extensions piled in an orderly manner with the sides positioned consistently.
By piling of the coils in an orderly manner, the space occupied by the coil in the core is optimized, therefore interference contact of the turns with the surrounding structure is avoided.
Normally, the two long sides of the rectangular extension of the coil are produced by the axial translations accomplished by the needles dispensing the wire. The rotation movements accomplished by the needles dispense the wire to form the two lateral stretches, which are usually the short sides of the coils. The incremental radial translations pile the turns in different planes of the coil, i.e. at various depths of the slots of the core—a phenomena usually referred to as “stratification” of the turns.
The needles are moved with kinematic solutions driven by rotation of an input motor to accomplish the foregoing movements, like is described in the above mentioned EP 1191672.
In publication EP 318 063 a more limited solution is described. In this case the needles do not move in the radial direction to achieve the stratification.
The different kinematic solutions existing in the art significantly influence both the precision with which the needles are positioned to form the coils, and also the speed with which the needles move to dispense the wire.
In other words, the kinematic solutions are important not only for the precision with which the turns become positioned in the coil, but also for the time required to place all the turns to form the finished coils. This is particularly influenced by the mechanical transmissions, the tolerances, the inertia of the parts of the various kinematic solutions, and also due to the position of these inertias in space.
The winding requirements of coils in brushless cores are particularly focused on positioning of the turns with the maximum precision within the available space of the core of the electric machine. At the same time, higher speed of the movement of the needles is required to increase productivity. The end result is a production of wound cores at high speed with the coils being compact and having a high number of turns.
A further objective is that the movement of the needles needs to be easily and accurately adjusted to adapt the winding parameters to a wide variation of core configurations. In particular, the translation movements, the rotation movements, and the radial displacement of the needles respectively need to cover paths, accomplish angles and travel at slot depths that allow the coil turns to be precisely positioned within specific geometries of the cores.
For the same reason, these movements of the needles need to be accomplished in different stages of a temporal cycle, which is required to wind the coils.
Based on the foregoing description, it is an object of the present invention to provide an improved apparatus for winding electric machine coils.
It is also a particular object of the invention to provide an improved apparatus that causes the needles to accomplish translation movements, rotation movements and radial movements with more accurate positioning of the needles during the winding stages.
It is also an object of the present invention to provide an improved apparatus for accomplishing the translation movements, the rotation movements and the radial movements of the needles at a higher speed to increase the productivity of wound coils.
It is also an object of the present invention to provide an apparatus that has solutions which are easily adjustable for winding different core configurations, whilst maintaining the foregoing advantages of positioning accuracy and high speed movement of the needles.
A further object of the invention is to provide an apparatus that is more simple to manufacture due to the low number of parts, and for the fact that the parts are of simple configuration and can be easily assembled.